Among the most critical populations for NIDA messages and information to reach are America's youth. They are at the highest risk for substance use and for that use to escalate into addiction. From NIDA-funded research we know that substance use and the perception of harm are closely related. By informing middle and high school students of the mental and physical health effects associated with substance use, as well as the consequences to other areas of their lives, NIDA can impact youths' perception of harm and decrease overall substance use and the related consequences.